The algorithm has the effect of reducing the data transmission speed by one third but
extending the effective range.
6.8
Address Mode ADDR
Typing Y to this option will enable the Address Mode. The modem will transmit its TXAD at
the start of each data string. It will not pass receiver data to the serial port unless the
transmitter address of the incoming data string coincides with its receiver address RXAD.
The transmitter address 00 is used as a global address. Hence all radio modems in range
regardless of its receiver address will pass the data string to its serial port.
An “AT” (Attention) instruction can be sent from the host to change both the receiver address
RXAD and the transmitter address TXAD.
6.8.1 Basic Configuration
When the address option is selected, two modems with the following address will pass data
to their Hosts.
TXAD Modem 1 = RXAD Modem 2
RXAD Modem 1 = TXAD Modem 2
No other modems in the network will be able to communicate with them. This is useful for
high security data is transfer.
6.8.2 Station Addressing
The ATRnn and ATTnn instruction can be used to
“
dial up” distant modems as shown in fig 4.
The base station modern has its receiver address set to 01. The four distant stations, modem
2 to modem 5, have their transmitter address set to 01. Therefore any distant modem can
transmit data to the base station but not to each other.
The base station can
dial up modem 2 by inserting the following instruction string at the start
of the data:
ATT02
In Hexadecimal code this will be:
A
T
T
0
2
41
54
54
30
32
Modem 3 can be dialled up in the same way with the instruction:
ATT03
The instruction string will not be transmitted over the air as long as it is sent to the modem
without any breaks.
